Why 72 Is the New 30

Babies born today are 200 times less likely to die in early life than if they were born a century ago.

At older ages, the chances of dying are also substantially lower now than they were just four generations ago.

A new study, which compared modern human lifespans with those of hunter-gatherers and chimpanzees, suggest that industrialization and development since 1900 -- not any genetic shift -- are responsible for our species' dramatic gains in life expectancy.

By touching on why aging and death happen at the rates they do, studies like this one could ultimately help us figure out which public health strategies will work best to extend lifespans.

Still unresolved are debates about how long humans can ultimately expect to live and whether the previous century's drops in mortality might continue at the same rate.

"In terms of the probability you'll live through the year, it's astronomical the improvement that we've made," said Oskar Burger, an evolutionary anthropologist at the Max Planck Institute for Demographic Research in Rostock, Germany.

"The probability that you'll live through the year in our evolutionary past that was experienced at age 30 or even 20 is now typical of people who are 70," he added. "Seventy-two is the new 30."

In the world's wealthiest nations, according to a 2002 study, life expectancy at birth has been increasing steadily at a rate of three months each year since 1840. That's a remarkable pattern, Burger said, especially for a trait that is so complicated and dependent on so many variables.